The present invention relates to an elastic coupling, and particularly an elastic coupling for a multi-mass flywheel in the drive line of a motor vehicle driven by an internal combustion engine
One elastic coupling of background interest is disclosed in Federal Republic of Germany OS 37 21 712. This known elastic coupling has a first mass which is associated with the drive engine and a third mass which is associated with the following transmission. Between the first and third masses is a second mass which is connected, separated from each of the first and third masses, via first and second springs. The masses are connected in each case in series via the springs in the direction of the flow of power. The spring arranged between the first mass and the second mass is a coil spring which expands in circumferential direction over a large angular region.
As a damping device, a substantially toroidally curved spring chamber is provided, the walls of which rest closely along the outer circumference of the spring turns. The coil spring contained in the spring chamber is supported in the circumferential direction by axial lugs. When the first and second masses turn relative to one another under the action of torque, a damping medium present in the spring chamber is displaced into adjacent regions of the interior space of the elastic coupling. The damping medium in this case flows through the inside of the coil spring past the spring support The cross-sections are, in this connection, very large, which can produce only a slight damping of the oscillations. If the damping medium is displaced out of the spring chamber it can only flow back again with a time delay, predominantly by centrifugal force, if the volume of the spring chamber changes only slightly under operating conditions with small amplitudes of oscillation. The known elastic coupling thus does not have the required damping properties under all conditions of operation and at all temperatures.
In addition, there is no way of adequately varying the damping force as a function of the angle of rotation. In particular, the damping force is constant at all angles of rotation. There is no suggestion of any adaptation of the damping energy or force to engine performance of torque, nor to the operating conditions of the vehicle drive.
Federal Republic of Germany Patent 28 48 748, which is equivalent to U.S. Pat. No. 4,351,167, discloses an elastic coupling which is provided on the periphery of the inner space with a plurality of displacement chambers of variable volume within which the damping medium is forced through throttle slots when the two elastic coupling halves turn, depending on the load. The damping of rotary oscillations inherent therein is substantially constant over the angle of turn. The damping force can be adapted to some extent as a function of the angle of turn with this elastic coupling, but still insufficiently in critical applications. See FIG. 4 and the steps 46, 49 in the throttle slots 45, 48. The main problem is obtaining optimal damping when idling and under partial load, under noncritical resonance conditions Slight damping is required when idling, with partial and full loads and when the vehicle is being pushed, while high damping is required when passing through the resonant speed of rotation and when the load changes. The structural form of this known displacement chamber also does not permit its installation in a multi-mass flywheel because of considerations of space.
Federal Republic of Germany Patent 36 41 962 discloses a solution which mechanically achieves a decoupling of oscillation when passing through the critical resonance region. The solution contemplated is, however, very cumbersome from a structural standpoint.
The disclosures of the prior art materials discussed herein are incorporated by reference.